package org.bouncycastle.asn1;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class DEROutputStream extends FilterOutputStream implements DERTags {
    public DEROutputStream(OutputStream os) {
        super(os);
    }

    private void writeLength(int length) throws IOException {
        if (length > 127) {
            int size = 1;
            int val = length;

            while ((val >>>= 8) != 0) {
                size++;
            }

            write((byte) (size | 0x80));

            for (int i = (size - 1) * 8; i >= 0; i -= 8) {
                write((byte) (length >> i));
            }
        } else {
            write((byte) length);
        }
    }

    void writeEncoded(int tag, byte[] bytes) throws IOException {
        write(tag);
        writeLength(bytes.length);
        write(bytes);
    }

    protected void writeNull() throws IOException {
        write(NULL);
        write(0x00);
    }

    public void write(byte[] buf) throws IOException {
        out.write(buf, 0, buf.length);
    }

    public void write(byte[] buf, int offSet, int len) throws IOException {
        out.write(buf, offSet, len);
    }

    public void writeObject(Object obj) throws IOException {
        if (obj == null) {
            writeNull();
        } else if (obj instanceof DERObject) {
            ((DERObject) obj).encode(this);
        } else if (obj instanceof DEREncodable) {
            ((DEREncodable) obj).getDERObject().encode(this);
        } else {
            throw new IOException("object not DEREncodable");
        }
    }
}
